Sheet feeding and aligning apparatus

ABSTRACT

An apparatus for aligning two sheets of veneer in parallel relationship and feeding the veneer while in that relationship to a receiving station with such apparatus including a section for storing several stacks of veneer, conveying means for advancing individual sheets of veneer from the storage stacks to an alignment section of the apparatus, laterally shiftable fences in the alignment section for moving the veneer into adjacent sideby-side relationship, and controls for automatically controlling the operation of the apparatus.

United States Patent [191 Short et al.

[ Feb. 20, 1973 [22] Filed:

[54] SHEET FEEDING AND ALIGNING APPARATUS [75 Inventors: Charles R.Short, Cupertino; Ronald J. Billett, Sunnyvale, both of Calif.

[73] Assignee: FMC Corporation, San Jose, Calif.

Nov. 8, 1971 [21] Appl. No.: 196,531

[52] U.S. Cl. ..271/9, 27l/52, 271/58,

271/59 [51] Int. Cl ..B65h 9/10, B65h 9/16 [58] Field 0i Search ..271/9,52, 53, 58, 59, 48,

[56] References Cited UNITED STATES PATENTS Stokes et al. ..271/48Charnock ..271/52 X 3,375,003 3/l968 Godlewski.... v.271/9 3,554,353l/l97l Raudat ....l98/30 3,603,463 9/l97l Billett et al. l98/79 PrimaryExaminerHarvey C. Hornsby Assistant Examiner-Bruce H. Stoner, Jr.Attorney-F. W. Anderson et al.

[57] ABSTRACT An apparatus for aligning two sheets of veneer in parallelrelationship and feeding the veneer while in that relationship to areceiving station with such apparatus including a section for storingseveral stacks of veneer, conveying means for advancing individualsheets of veneer from the storage stacks to an alignment section of theapparatus, laterally shiftable fences in the alignment section formoving the veneer into adjacent side-by-side relationship, and controlsfor automatically controlling the operation of the apparatus.

14 Claims, 17 Drawing Figures PATENTED FEBZO 1975 SHEET 4 BF 9 PATENTEBFEBZO 191s SHEET 6 BF 9 SHEET FEEDING AND ALIGNING APPARATUS BACKGROUNDOF THE INVENTION 1. Field of the Invention The present inventionpertains to apparatus for feeding and aligning sheet material, and moreparticularly, it pertains to apparatus for feeding and aligning sheetsof veneer.

2. Description of the Prior Art In the plywood fabricating art, it is afrequent practice to use two half-sized sheets of veneer (commonlycalled split-center veneer) aligned in side-by-side relationship tocomprise one of the middle lamina of the plywood. Even though there areplywood fabricating machines that store sheets of veneer andautomatically advance the sheets to an assembling station, to applicantsknowledge, no apparatus is available that will align and feedsplit-center veneer. Prior to the present invention it was necessary toprovide at least one, and normally two, workers to feed thesplit-centered middle lamina to the assembling station of the plywoodfabricating machines. This, of course, added many man-hours of labor tothe cost of fabricating plywood. Accordingly, the plywood industry hasfor some time been desirous of an apparatus that will eliminate thisburdensome labor overhead.

SUMMARY OF THE INVENTION The apparatus of the present invention isadapted to simultaneously remove one sheet at a time from several stacksof sheet material and align the several sheets in adjacent parallelrelationship whereby they can be fed in this relationship to a receivingstation.

In a preferred embodiment of the invention the apparatus is comprised ofan alignment section where two sheets which have been removed from thestacks are aligned along their opposed longitudinal edges and moved intoclosely spaced positions for feeding to a receiving station.

The apparatus of the present invention is provided with means which areautomatically operated to feed sheets of material upon a conveyor.Longitudinally extending fences positioned above the conveyor defineareas thereon into which the individual sheets pass. The fences aretransversely movable whereby sheets lying therebetween can be shiftedinto adjacent side-by-side relationship and properly aligned for feedingto a receiving station. The sheets are held in adjacent parallelrelationship until a retaining gate at the output end of the conveyor isopened by the operator of the apparatus to allow the sheets to be fed tothe receiving station by the conveyor. The apparatus itself is fullyautomatic. Manual assistance is required to operate the retaining gateonly when it is desired that the previously aligned sheets be fed to thereceiving station.

Accordingly, it is an object of the present invention to provide anapparatus for aligning sheets of material in adjacent side-by-siderelationship.

It is another object of the present invention to provide an apparatusfor automatically removing individual sheets of material from storedstacks of the material and aligning the individual sheets in adjacentside-by-side relationship.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of thealignment apparatus of the present invention with portions thereof beingbroken away for the purpose of clarity.

FIG. 2 is an isometric view of a plywood fabricating machine whichincorporates the alignment apparatus of FIG. 1.

FIG. 3 is an enlarged top plan of a portion of the alignment apparatusof FIG. 1 with parts thereof being broken away for the purpose ofclarity.

FIG. 4 is a fragmentary isometric view of the input end of the alignmentapparatus of FIG. 3 particularly showing the drive mechanism for thefeed rollers and the sheet advancing rollers.

FIG. 4A is an enlarged section taken on the line 4A-4A of FIG. 3particularly showing the clutchbrake arrangements for controlling thefeed rollers.

FIG. 5 is an enlarged transverse section taken along line 55 of FIG. 3.

FIG. 6 is an enlarged transverse section taken along line 66 of FIG. 3.

FIG. 7 is an enlarged longitudinal section taken along line 77 of FIG. 5with portions of the alignment apparatus being broken away.

FIG. 8 is an enlarged longitudinal section taken along line 88 of FIG. 5with portions of the alignment apparatus being broken away.

FIG. 9 is a section taken along line 9-9 of FIG. 8 particularly showingthe means for connecting the two fences of the alignment apparatus ofFIG. 3.

FIG. 9A is an enlarged diagrammatic side elevation, taken generally inthe direction of the arrows 9A-9A of FIG. 3, particularly showing theconstruction and operation of the gate used to selectively block thepassage of sheet material through the apparatus of the presentinvention.

FIGS. 10 and 10A are diagrammatic representations of the controlcircuitry for the alignment apparatus of the present invention.

FIGS. 11A, 11B, 11C and 11D are diagrammatic plan views of the alignmentapparatus of FIG. 1 illustrating its manner of operation.

DESCRIPTION OF A PREFERRED EMBODIMENT For purposes of illustration andin order to disclose a specific application for the aligning apparatus20 (FIG. 1) of the present invention, such apparatus will be describedherein in connection with its use as a component of the plywood lay-upmachine such as disclosed in US. Pat. No. 3,603,463 and 3,598,252 toBil- Iett et al. It is to be understood, however, that the apparatus ofthe present invention would find utility in other systems wherein it isdesired to align sheets of material in adjacent side-by-siderelationship.

Referring now to FIG. 2, a plywood lay-up machine 22, of the typedisclosed in the aforementioned US. Pat. No. 3,603,463 and 3,598,252, isthere shown and will be seen to include a storage station 24 having astack of back veneer B, a storage station 26 having a stack of faceveneer F, the aligning apparatus 20 of the present invention which has astorage section 28 for adjacent stacks MI and M2 of half-sized sheets ofmiddle veneer and an alignment section 30, and an assembly station 32where the various veneer which comprise a sheet of plywood areassembled. The lay-up machine 22 is operated by two workers A and Dlocated at the assembly station 32. Worker A is responsible forsequentially delivering the various veneer from the storage stacks alongan overhead roller conveyor 33 to the assembly station by the use ofelectromechanical means which are operated by control switches 34 at theassembly station. Worker D is responsible for feeding core strips Cthrough a gluing machine 36 at the assembly station in a manner suchthat worker A can lay the strips across and between the various veneerlaminae in each sheet of assembled plywood. The assembled sheets ofplywood are accumulated in a stack P at the assembly station 32 beforethey are individually pressed and trimmed in apparatus that is notdisclosed herein. In the disclosed arrangement of the plywood lay-upmachine, the sheets of veneer used for the middle lamina areapproximately half the width of the back and face veneer. The stacks M1and M2 of the middle veneer are arranged in spaced side-by-siderelationship whereby after the veneer have been singulated, properlyaligned, and moved into closely adjacent side-by-side relationship inthe alignment section 30 of the apparatus, each pair of middle veneerwill comprise a lamina which is substantially equivalent in size to eachof the back and face veneer laminae.

The alignment apparatus is best seen, from an overall viewpoint, in FIG.1 wherein the storage section 28 of the apparatus will be seen toinclude a generally rectangular frame structure 37 and a pair ofidentical, independently operated, scissors-type lift tables, orelevators, 38 and 40, which may be of the type disclosed in US. Pat. No.3,110,476 issued to W. A. Farris. The elevators respectively support thestacks M1 and M2 of the middle veneer on platforms 42 and 44, and thevertical movement of the platforms is regulated by identical,single-acting pneumatic cylinders 46, as will be explained more clearlyhereinafter.

The frame structure 37 of the veneer storage section 28 has twolongitudinally extending side members 50 along the top portion thereof,each member having on its outermost side an outwardly projecting track52 (only one being shown in FIG. 1). Each track is adapted to supportand guide a pair of rollers 54 which are rotatably mounted on laterallyextending angled end portions 56 of a carriage 58, whereby the carriageis free to roll along the tracks 52 in a horizontal plane adjacent thetop of the storage section. A double-acting pneumatic cylinder 60 isanchored to a cross member 61 of the frame 37 at its upstream end (theend furthest removed from the alignment section 30), and the projectingpiston rod 60a of the cylinder 60 is attached to the carriage 58 so thatextension and retraction of the piston rod will cause the carriage toreciprocate in the aforementioned plane.

Mounted on the carriage 58 in vertical alignment with the elevators 38and 40 are identical vacuum heads 62 and 64, respectively. These vacuumheads may be similar to the vacuum heads disclosed in US. Pat. No.3,599,968 to Billett et al., and will not be described in particulardetail herein since the details of such structures are not critical toan understanding of the present invention. In general, these vacuumheads are characterized by a flexible skirt 66 at the bottom thereof,which is adapted to slide across the uppermost veneer in the associatedunderlying stack M1 and M2 and to hermetically seal the vacuum headagainst the uppermost veneer when a suction fan inside a housing 67 ofthe vacuum head is operated. Thus, subsequent movement of the carriage58 will result in the corresponding movement of the veneer.

An elongated, transversely extending throat 68 comprising upper andlower guide members 70 and 72, respectively, is mounted across thedownstream end of the storage section 28 of the apparatus 20 and at anelevation above the ground approximately the same as the elevation ofthe skirts 66 of the vacuum heads. The opposed guide members 70 and 72are flared outwardly in the upstream direction whereby sheets being fedinto the throat by the vacuum heads 62 and 64 will emerge from therestricted portion of the throat and be presented to the alignmentsection 30 of the apparatus in a narrow horizontal zone immediatelyadjacent two vertically arranged pairs of nip rollers 74 and 76comprised of intermittently driven feed rollers 74a and 76a,respectively, and associated idler rollers 74b and 76b, respectively(FIG. 4).

The alignment section 30 includes, in addition to the pairs of niprollers 74 and 76, a frame 77 which is connected to and aligned with theframe 37 of the storage section, a plurality of continuously drivenfriction conveyor rollers 78 arranged in a horizontal plane on theframe, a longitudinally extending outside fence 80 and a center fence 82that are both positioned for lateral movement between the rollers, and astationary side wall 84 adjacent one end of each of the rollers.

The feed rollers 74a and 76a (FIG. 4) are driven by a motor 86 actingthrough a gear box 88. A chain 99 is trained around a sprocket 100 thatis fixed on the output shaft 102 of the gear box 88 which chain drives asprocket 104 that is part of a free-wheeling doublesprocket unit 106rotatably disposed on a drive shaft 108 carrying one of the lower feedrollers 74a. The drive shaft 108 is journalled at one end in a housing109 and at the other end in a bearing (FIG. 4A) in a longitudinallyextending frame member 111 of the frame 77. The other sprocket of thedouble sprocket unit 106 mounts one end of a drive chain 116 the otherend of which is secured about a free-wheeling sprocket 112 that isrotatably mounted upon a transfer shaft 114. The transfer shaft 114 liestransversely of the aligning apparatus 20 below the drive shaft 108 andis journalled at one end thereof in the longitudinally extending framemember 111 (FIG. 4A) and at the other end thereof in a secondlongitudinally extending frame member 129 of the frame 77. Fixed on theend of the transfer shaft 114 that is journalled in frame member 129 isa sprocket 122 which is in driving connection with a sprocket 124through an endless drive chain 128. The driven sprocket 124 is fixed ona drive shaft 126 carrying the lower feed roller 76a. The drive shaft126 is journalled at one end in the housing 109 and at its other end inthe longitudinally extending frame member 129 of the frame 77. It willbe appreciated that the transfer shaft 114 provide a driving connectionbetween the drive motor 86 and the drive shaft 126 supporting the feedroller 76a.

Clutch-brake mechanisms 96 and 98, which provide for the transfer ofdriving power to the shafts 108 and 114 respectively, may be of the typedesignated FWCB manufactured by Horton Manufacturing Co., Inc. ofMinneapolis, Minn. The clutch-brake mechanisms are identical and arebasically comprised of a brake portion and a clutch portion. As isconventional, the clutch portion has a driving member and a drivenmember which are spring biased into disengaged positions but which areengageable if the spring bias is overcome by pneumatic pressure appliedto the driven member through a pressure line. The brake portion isindependent of the clutch portion and operates similarly in that abraking member is biased out of engagement with a movable plate membersplined on the drive shaft on which the clutch brake mechanism ismounted. However, when the bias is overcome by pneumatic pressuresupplied through a second pressure line, the braking member engages themovable plate member to stop rotative movement. Both pressure lines areconnected at their other ends to a two-position solenoid valve which isoperative to engage the clutch or the brake separately, but never toengage both of them together. Therefore, when the clutch is engaged thebrake is always disengaged, and when the brake is engaged the clutch isalways disengaged.

Clutch brake mechanism 96 is mounted on drive shaft 108 of feed roller740 (FIG. 4A) in a manner such that the driven member of the clutch iskeyed to the drive shaft 108 for unitary rotation with the drive shaft,and the driving member of the clutch is bolted to the sprocket 104 ofthe double sprocket unit 106 for unitary rotation therewith. It cantherefore be seen that when the clutch is disengaged, the doublesprocket unit 106 will continue to be rotated by the motor 86 actingthrough the drive chain 99 but the drive shaft 108 will remainmotionless with the brake portion of the clutchbrake mechanism 96preventing the shaft from rotating. When the clutch is engaged, in amanner to be explained later, the brake will release and the drivingmember of the clutch will move into operative engagement with the drivenmember of the clutch causing the drive shaft 108 and the feed roller 74afixed thereon to begin rotating. Thus the feed roller can be rotated andstopped through operation of the clutch-brake mechanism 96.

The clutch-brake 98 is mounted on the transfer shaft 114 (FIG 4A) in amanner such that the driven member of the clutch is keyed to thetransfer shaft 1 14 for unitary rotation therewith and the drivingmember of the clutch is bolted to the sprocket 112 which is arranged tobe continuously driven through drive chain 116. It can therefore be seenthat when the clutch is disengaged, the sprocket 112 will continue to berotated by the motor 86 but the transfer shaft 114 will remainmotionless with the brake portion of the clutch-brake mechanism 98preventing the transfer shaft from rotating. When the clutch portion ofthe clutch-brake mechanism 98 is engaged, in a manner to be explainedlater, the brake will release and the driving member of the clutch willmove into operative engagement-with the driven member of the clutchcausing the transfer shaft 114, and consequently the feed roller 76a, torotate. Thus feed roller 76a can be rotated and stopped throughoperation of the clutch brake 98. It is evident, however, that eventhrough the motor 86 is continuously running, the feed rollers 74a and76 a can be alternately driven and stopped independently of each other.

The support shafts for the idler rollers 74b and 76b are joumalled atone end in a bearing housing 131 supported from a cross frame member 133at the center thereof. The other end of the support shaft for roller 74bis joumalled in a support post 111a mounted on frame member 111 (FIG.4A) and the other end of the support shaft for roller 76b is joumalledin a support post mounted on frame member 129.

The motor 86 is also utilized to continuously rotate the conveyorrollers 78 which are joumalled in bearings (FIGS. 3 and 8) mounted inthe longitudinally extending frame members 111 and 129 of the frame soas to lie in a horizontal plane. The motor is connected through a secondgear box 132 (FIG. 4) to a drive shaft 134 having a drive pulley 136fixed on the outer end thereof. A plurality of idler pulleys 138(smaller in diameter than the drive pulley 136) are mounted in bearings140 (FIGS. 5 and 6) disposed in the longitudinally extending framemember 111 of the frame 77 whereby the axes of rotation of the idlerpulleys 138 are parallel to the longitudinal axis of the drive shaft134. Near the downstream end of the longitudinally extending framemember 111, an idler pulley 141, identical in size to the drive pulley136, is mounted with its rotational axis also parallel to thelongitudinal axis of the drive shaft 134. A friction belt 142 is trainedaround the drive pulley 136 and the idler pulley 141, and the driveshaft 134 is arranged to be rotated in the direction of the arrow inFIG. 4 so as to cause the veneer which rests atop the conveyor rollers78 to be moved longitudinally down the conveyor between the side framemembers 111 and 129 thereof. The friction belt 142 is guided andsupported by the smaller idler pulleys 138. It can be seen from FIGS. 4,5 and 6 that the idler pulleys 138, on which the friction belt 142rides, are disposed at an elevation slightly lower than the conveyorrollers 78 so that the conveyor rollers 78 will rest against and berotated in a clockwise direction, as viewed in FIG. 4, by the frictionbelt 142 as it is continuously driven by the motor 86.

The horizontal conveyor rollers 78 are mounted on the frame 77 so thatthey lie at an oblique angle to each of the longitudinally extendingframe members 1 1 1 and 129 with the end supported by frame member 129slightly advanced of the end supported by frame member 111 (FIG. 3).With the rollers so mounted and caused to rotate, it will be apparentthat the sheets of veneer being supported by the rollers will be urgedtoward the frame member 111 while they are simultaneously advancedtoward the forward end of the alignment section 30 and into engagementwith a stationary gate 144 (FIG. 3).

As mentioned previously, the alignment section 30 of the apparatus isprovided with a stationary side wall 84, a movable outside fence 80, anda movable center fence 82. It is also provided at the forward endthereof with a transversely extending gate 144 that is normally closedto block the forward movement of the veneer on the rollers 78 but whichcan be opened, in a manner to be described hereinafter, to permit thealigned veneer to pass.

The outside fence 80 is normally disposed adjacent the frame member 129as shown in FIG. 3, but under certain conditions it can be movedlaterally toward the longitudinal center of the alignment section 30.The outside fence includes a longitudinally extending tubular bodymember 146 (FIGS. 5, 6 and 8) that lies beneath the level of theconveyor rollers 78 and supports, through a plurality of rigid uprightmounting brackets 148 interspaced between every fourth conveyor roller,an inverted L-shaped sheet engaging plate 150. As shown in FIG. 3, theplate 150 extends parallel to the adjacent side frame member 129 over agreater part of the length of the alignment section. Welded to theunderside of the tubular body member 146 and extending parallel to andinwardly toward the center of the overlying conveyor rollers 78 is anangle iron bracket 152 (FIGS. 6 and 8) with an abutment plate 154 weldedonto its innermost end. A pair of support and guide rollers 156 arerotatably mounted on the angle iron bracket 152 and are provided withcircumferential grooves so that they can ride upon a rail 1S8 runningbeneath and parallel to the angle iron bracket. The outside fence 80 cantherefore be rolled along the cylindrical rail 158 to thereby shift thelateral position of the fence with respect to the veneer conveyor. Therail 158 is supported by a plurality of rigid strips 159 welded to theunderside of a tubular frame member 161 which is secured at its ends tothe side frame members 111 and 129. Upstream from the rail 158 is asecond cylindrical rail 160 running parallel to and at the sameelevation as rail 158. A support roller 162, which is rotatably mountedon a depending bracket 164 attached to the tubular body members 146, isarranged to be received upon the rail 160 (FIG. 8). The rail 160 issupported on a plurality of rigid strips 165 which are welded to theunderside of a second tubular frame member 167 that lies transversely ofthe frame 77 and is secured at its ends to the side frame members 111and 129. The roller 162 is provided to give additional support to theoutside fence 80 whereby it can be easily shifted transversely to thedirection of movement of the veneer.

The outside fence 80 is retained in its normal position adjacent sideframe member 129 by a pneumatic cylinder 166 (FIG. 3) whose piston rod168 in its extended position engages the end abutment plate 154 (FIG. 6)on the supporting angle iron bracket 152. A coil spring 170 (FIGS. 3 and8) enclosed in a tubular housing 171 has one end attached to a bracket169 (FIG. 6) depending from a longitudinally extending tubular framemember 174 which comprises a portion of the stationary side wall 84. Theother end of the coil spring is attached to a turnbuckle 172 which isconnected to a bracket 172a (FIG. 8) depending from the outside fence.The coil spring 170 therefore serves to bias the outside fence towardthe longitudinal center of the alignment section under the restraint ofthe cylinder 166 and its projecting piston rod 168. The housing 171 forthe spring 170 is supported by rigid strips 173 welded to the undersideof the tubular bracket 161 adjacent to the rigid strips 159 whichsupport the guide rail 158.

The center fence 82 is normally disposed (FIG. approximately along thelongitudinal center of the alignment section 30, but under certaincircumstances it can be laterally shifted toward the stationary sidewall 84. The center fence includes a longitudinally extending tubularbody member 186 that lies parallel to and approximately at the sameelevation as the body member 146 of the outside fence. The body member186 supports, through a plurality of rigid upright brackets 187interspaced between every fourth conveyor roller 78, a generallyT-shaped sheet engaging plate 188 that extends longitudinally of thealignment section 30 for approximately the same distance as the plate ofthe outside fence (FIG. 3). Welded to the underside of the tubular bodymember 186 and extending parallel to the conveyor rollers 78 toward theside wall 84 is an angle iron bracket 190 with an abutment plate 192(FIGS. 6 and 7) depending therefrom near its center portion. A pair ofsupport and guide rollers 194 are rotatably mounted on the angle ironbracket 190 and are provided with circumferential grooves which arearranged to be received upon a cylindrical rail 196 running parallel toand adjacent the rail 158 whereby the center fence can be shiftedlaterally with respect to the conveyor. Rail 196 is supported by thesame rigid strips 159 which support the rail 158. A support roller 200is rotatably attached to a depending bracket 202 (FIG. 7) on theupstream end of the tubular body member 186 so as to ride on the rail160, similarly to the roller 162 on the outside fence, so that thecenter fence can be easily shifted in the lateral direction.

The center fence is retained in its normal position near the center ofthe alignment section 30 by a pneumatic cylinder 204 (FIGS. 3, 6 and 7)whose piston rod 206, in its extended position, engages the abutmentplate 192 on the depending angle iron bracket 190 and pushes the fenceagainst a fixed stop member 203 (FIG. 5) mounted atop the tubular framemember 167. The center fence may be caused to shift toward side wall 84if the piston rod 206 is retracted. If a sheet of veneer is lyingbetween the center fence and the outside fence when the outside fence ispulled laterally toward side wall 84 by the coil spring 170, it will bepinched between the fences to transmit the lateral movement of theoutside fence to the center fence and thereby move the center fencetoward the side wall 84.

The side wall 84 is comprised of a flat plate 207 arranged to overliethe veneer on the conveyor rollers 78. The plate is supported by aplurality of cylindrical posts 208 which are positioned between theconveyor rollers and which are mounted upon the upper surface of thetubular frame member 174.

It will be noted that the side wall 84, the center fence 82, the outsidefence 80, and the gate 144 normally define a pair of longitudinallyextending pockets 210 and 212 (FIG. 3) for receiving a pair of sheets ofveneer fed by the feed rollers 74 and 76. It will be apparent that thesheet in pocket 210 will be urged by the conveyor rollers 78 against theside wall 84 as it is advanced to the gate 144 while the sheet in pocket212 will be simultaneously urged against the center fence 82 as it isadvanced by the conveyor rollers.

The gate 144 (FIGS. 3 and 9A) comprises an angle member 214 which ismounted upon a rod 218 that extends between the side frame members 111and 129. The rod has its end portions pivotally mounted in bearingsdisposed on the side frame members so that the angle member 214 is freeto move between an upright position, as shown in solid lines in FIG. 9A,and a lowered position, as indicated in phantom lines in FIG. 9A. In itsupright position, the gate is seen to extend above the level of theconveyor rollers 78 where it will obstruct sheets of veneer beingsupported and conveyed by the conveyor rollers. The gate member 214pivots about the axis of the rod 218 in response to A movement of a link220 rigidly attached to the end of the rod which projects through theside frame member 129. A pneumatic actuator 222 is pivotally mounted ona pin 224 attached to the side frame member 129. The actuator includes aprojecting piston rod 226 having a head 226a which is pivotallyconnected to the link 220 for moving the gate between its two operativepositions. It is apparent that when the piston rod 226 is extended (tothe solid line position of FIG. 9A) the gate will be closed to retainsheets of material in the alignment section 30 upon the conveyor rollers78, but when the piston rod is retracted (to the phantom line positionshown in FIG. 9A) the gate will be opened to allow the sheets ofmaterial to be advanced, e.g., to the assembly station 32 of a plywoodlay-up system. The operation of the pneumatic actuator 222 can becontrolled manually by a worker A (FIG. 1) at the assembly station whowill feed the aligned sheets forwardly when needed.

The aligning apparatus is designed so that it can also feed full-sizedsheets of middle veneer to the assembly station 32 rather than thehalf-width sheets described hereinbefore. When using the aligningapparatus to feed full-sized sheets, the center fence 82 is secured tothe outside fence 80 so that full-sized sheets can be fed onto theconveyor rollers 78 by the nip rollers 74 and 76. To secure the centerfence to the outside fence the depending plate 172a of the tubular bodymember 146 (FIG. 9) mounts a latch 232 adapted to removably receive apin 234 carried by bracket 236 depending from the tubular body member186 of the center fence. To latch the two fences together, it is onlynecessary to remove the stop member 203 mounted on the frame member 167and roll the center fence 82 along its supporting rails 196 and 160toward the side fence 80 until the two fences contact each other andbecome latched. When latched, the two fences will move as a unit andwill follow the same operative pattern that the outside fence followsduring normal operation.

The operation of the aligning apparatus 20 of the present invention iscontrolled by a plurality of switches and photocells which operate tocause the sheets of veneer to be advanced from the storage section 28 ofthe apparatus through the alignment section 30 and into the assemblystation 32.

As can be seen in FIG. 1, four limit switches are mounted on the framestructure 37 of the storage section 28 of the apparatus two normallyclosed limit switches ILS and 2LS being located above and in verticalalignment with the stack M] of veneer, and two normally closed limitswitches 3LS and 4LS being located above and in vertical alignment withthe stack M2 of veneer. Limit switches 11.5 and 3LS, at the rearwardends of the stacks, serve to sense the elevation of the respectivestacks of veneer. These switches are operative, through a controlcircuit to be described later, to maintain the elevation of theuppermost veneer in the stacks at a predetermined elevation adjacent theundersides of the corresponding vacuum heads 62 and 64. The normallyclosed limit switches 2LS and 4LS, which are located forwardly ofswitches lLS and 3LS, are held open by the uppermost veneer in anassociated stack (similarly to the switches lLS and 3LS) but are allowedto close when the switch arm of either of the limit switches swings downthrough an aligned opening (not shown) in the corresponding supportplatform 42 and 44 when the last, or bottom, veneer is removed from theassociated stack.

A normally closed limit switch SLS (FIG. 1) is mounted on the base framestructure of elevator 40 in a position where it will be opened by thesupport platform 44 when the platform is in its lowermost position. Anidentical limit switch (not shown) is mounted on the frame of elevator38 for the same purpose.

A pushbutton lPB is mounted on one of the vertically extending posts ofthe frame structure 37 (FIG. 1) and is operative to raise the platform44 of the elevator 40 by means of circuitry to be described hereinafter.Another pushbutton 2PB is provided in a location adjacent pushbutton lPBfor lowering the platform 44. Similar pushbuttons 3PB and 4PB areprovided adjacent to pushbutton lPB for raising and lowering,respectively, the platform 42 of elevator 38.

Referring now to FIG. 10, a circuit diagram is there shown forcontrolling the operation of the elevators 38 and 40. Inasmuch as thecontrol circuit for the elevator 38 is identical to the control circuitfor elevator 40, only the circuit for elevator 40 will be described. Itis to be understood that the circuitry 252 controlling the operation ofthe elevator 38 would correspond identically to the circuitry 250 forcontrolling the operation of elevator 40. Looking at the circuitry 250,it will be seen that pushbutton lPB is connected to the input setterminal 254 of a flip-flop circuit 256. Pushbutton 2PB is connected toone input terminal 258 of an OR gate circuit 260 whose output 261 isconnected through a monostable multivibrator or one shot circuit 263 tothe input reset terminal 262 of the flip-flop 256. The OR gate circuit260 has two other input terminals 264 and 266 which are connected to thelimit switches 2LS and 4LS respectively. The output terminal 268 of theflip-flop 256, which has a logit 1 (as indicated) when the flip-flop hasbeen set, is connected to an input terminal 270 of an AND gate circuit272. The only other input terminal 274 of the AND gate circuit 272 isconnected to the normally closed limit switch 3L8. The output 276 of theAND gate circuit 272 is connected to a solenoid lSOL that is operableconnected to a valve (not shown) controlling the flow of air to thedoubleacting cylinder 46 of the elevator 40 to cause the cylinder toraise the platform 44 when the solenoid is energized. The outputterminal 278 of the flip-flop 256, which has a logic 0 (as indicated)when the flip-flop has been set, is connected to an input terminal 280of an AND gate circuit 282. The only other input terminal 283 of the ANDgate circuit 282 is connected to the normally closed limit switch SLS.The output terminal 284 of the AND gate circuit 282 is connected to asolenoid 2SOL that is operably connected to a valve (not shown)controlling the flow of air to the double-acting cylinder 46 to causethe cylinder to lower the platform 44 when the solenoid is energized.When neither of the solenoids ISOL or 2SOL are energized, the controlvalve for the cylinder 46 assumes a neutral locking position in whichthe platform 44 is maintained at a constant height.

It will thus be seen that when the elevator 40 is in its lowered loadingposition, the limit switches 3L8 and 4L8 will be closed and limit switchSLS will be held open by the platform 44. To raise the platform 44, itis only necessary to press pushbutton IPB to set flip-flop 256 toprovide a positive potential on input terminal 270 of the AND gatecircuit 272. Inasmuch as the closed limit switch 3LS places a positivepotential on the other input terminal 274 of the AND gate circuit 272, apositive potential will be placed on output terminal 276 to energize thesolenoid 1SOL to cause the elevator cylinder 46 to extend and therebyraise the platform 44. The platform will continue to rise until theuppermost veneer in the stack M2 contacts and opens the limit switches4LS and 3LS. The opening of limit switch 3L8 (which occurs last) breaksthe circuit through AND gate circuit 272 thereby de-energizing thesolenoid ISOL and stopping the upward movement of the platform. Afterseveral veneer have been removed from the stack M2 by the vacuum head 64and fed to the alignment section 30 of the apparatus, the elevation ofthe uppermost veneer in the remainder of the stack will be at anelevation to allow limit switch 3LS to close. The closing of limitswitch 3LS will again energize solenoid ISOL, as before described, tocause the platform to raise until limit switch 3L8 is again opened bythe uppermost sheet of veneer. By this process the elevation of theuppermost veneer in the stack is self regulated so that the uppermostveneer is always immediately adjacent the vacuum head 64 for positiveremoval by the vacuum head. It should be noted that the switch arm oflimit switch 4L8 has a longer throw than the switch arm of limit switch3LS, whereby the limit switch 4LS does not close each time severalsheets of veneer have been removed from the stack. However, when thelast sheet in the stack has been removed, the switch arm of limit switch4LS falls through an opening (not shown) in the support platform 44allowing the switch to close. It can be seen in FIG. that when eitherlimit switch 4L8 associated with elevator 40 or the corresponding limitswitch 2L5 associated with elevator 38 closes, a positive potential isplaced on the output terminal 261 of the OR gate circuit 260 to producea pulse from the one shot circuit 263 and reset the flip-flop 2S6thereby placing a positive potention on the output terminal 278. Apositive potential is thereby placed on the input terminal 280 of theAND gate circuit 282. Since a positive potential is placed on the otherinput terminal 283 of the AND gate circuit 282 through closed limitswitch SLS, a positive potential is placed on the output terminal of ANDgate circuit 282 to energize solenoid ZSOL. Energization of solenoid2SOL, as stated hereinbefore, causes the cylinder 46 to lower theplatform 44. Thus, when the last veneer is removed from either stack M1or M2, the platform 44 will be caused to lower. It will be evident thatthe selective depression of push button 2P8 will also cause the platformto lower even if neither limit switch 4LS or 2L8 are closed.

In a similar manner, a circuit 252 (the details of which are similar tocircuit 250 and are not shown) controls the operation of elevator 38through solenoids 3SOL and 4SOL which cause the platform 42 of elevator38 to be raised and lowered respectively.

As was stated hereinbefore, the aligning apparatus 20 is adapted tohandle full-sized veneer as well as halfsized veneer. When the fencesand 82 are latched together and it is desired to handle fullsizedveneer, the elevators 38 and 40 can be caused to operate together byplacing the switch arms of two toggle switches lTS and 2TS (FIG. 10) onterminals 286 and 288 respectively. This will connect solenoid ISOL tosolenoid 3SOL through a line 290 and will connect solenoid 2SOL and 4SOLthrough a line 292. It will thus be apparent that with the respectivesolenoids so connected, they will be caused to work together regardlessof whether they get current from circuit 250 or from circuit 252.

As stated hereinbefore, the nip rollers 74 and 76 in the alignmentsection 30 of the apparatus are intermittently driven by the motor 86through clutch-brake mechanisms 96 and 98 respectively. The operation ofthe clutch-brake mechanisms 96 and 98 (previously described) iscontrolled through a pneumatic system (not shown) by solenoids SSOL and6SOL respectively (FIG. 10A) which operate valves to permit thepneumatic pressure lines to the brake members and clutch members to beopened and closed. When solenoid SSOL is energized, clutch-brakemechanism 96 is operative to provide a continuous drive to the feedroller 74a so that a sheet of veneer can pass into the alignment section30. The same is true for solenoid 6SOL which controls the drive to feedroller 76a.

The solenoids SSOL and 6SOL are energized when it is necessary to drivesheets of veneer into the alignment section 30 of the apparatus.However, they will be deenergized if the fences 80 and 82 and gate 144are not in the proper positions to receive the sheets of veneer or ifother sheets of veneer are already in the alignment section. As can beseen in FIGS. 1 and 3, a conventional photocell lPC is mounted on theframe 77 of the alignment section in a position below the nip rollers 76wherein it can sense the presence of a sheet of veneer which has justemerged from the downstream side of the nip rollers. A reflector (notshown) is mounted vertically above the photocell and above the level ofthe nip rollers 76 and is used to return the ray of light emanating at alocation directly adjacent to the photocell so that it can be detectedby the photocell. A corresponding photocell 3PC (whose correspondingreflector is also not shown) is mounted on the frame 77 to sense thepresence of a sheet of veneer which has just emerged from the downstreamside of the nip rollers 74. Longitudinally aligned with the photocellsIPC and 3PC and mounted on the frame 77 to sense the presence of veneeradjacent the gate 144 are two additional photocells 2PC and 4PC withadjacent light sources. The corresponding reflectors for directing thebeam of light back to the photocell are mounted on the conveyorstructure above the sheet feeding and aligning apparatus 20 of thepresent invention and are not shown. It will be apparent that photocell2PC will sense the presence of a sheet of veneer which is adjacent thegate 144 and in pocket 212 and that photocell 4PC will sense thepresence of a sheet of veneer which is adjacent the gate 144 and inpocket 210. Referring to FIGS. 3 and 5-8, it will be seen that threelaterally spaced limit switches 6LS, 7LS and 9L5 are mounted upon thedownstream side of the tubular frame member 167 which runs parallel tothe conveyor rollers 78 and connects the two side frame members 111 and129. The limit switches 6L5, 7LS and 9LS serve to sense the position ofthe fences 80 and 82. It can be seen that switch contacting arms 300 and302, connected to the underside of outside fence80--and center fence 82,respectively, are used to operate the limit" switches. Switch contactingarm 300 closes the normally open limit switch 6LS when the outside fenceis retracted adjacent the side frame member 129, (FIG. and switchcontacting arm 302 closes the normally open limit switch 7LS when thecenter fence 82 is retracted to its center position (FIG. 5) inengagement with stop member 203. The normally open-limit switch 9LS willbe closed by the contacting arm 300 when the outer fence 80 is movedinwardly toward center fence 82. Another normally open limit switch 8L5(FIG. 9A) is mounted on a projecting bracket 303 connected across thedownstream end of the frame 77 and is used to sense the position of thegate 144. When the gate 144 is upright in its sheet retaining position,the limit switch 8LS will be held closed.

The circuitry for operating the various aforedescribed components of thealignment apparatus of the present invention is shown schematically inFIG. 10A. For the purpose of clarity and ease of illustration various ofthe photocells and limit switches are shown in more than one circuit, itbeing understood that each limit switch may comprise several sectionsoperative in different circuits and that each photocell may control arelay which actuates contacts in several difierent circuits.

Referring now more particularly to FIG. 10A, it can be seen that thephotocell lPC is connected to one input terminal 308 of an OR gatecircuit 310 the output of which is connected to the solenoid 6SOL of theclutch-brake mechanism 98. The other input terminal 312 of the OR gatecircuit 310 is connected to the output terminal 314 of an AND gatecircuit 316. The AND gate circuit 316 has an input terminal 318connected to the normally open limit switch 6LS, an input terminal 320connected to the normally open limit switch 7LS, an input terminal 322connected to the normally open limit switch 8LS, and an input terminal324 connected to the photocell 2PC.

Similarly, it can be seen that the photocell 3PC is connected to oneinput terminal 326 of an OR gate circuit 328 whose output terminal 330is connected to the solenoid SSOL of the clutch-brake mechanism 96. Theother input terminal 332 of the OR gate circuit 328 is connected to theoutput terminal 334 of an AND gate circuit 336. The AND gate circuit 336has an input terminal 338 connected to the normally open limit switch6L8, an input terminal 340 connected to the normally open limit switch7LS, an input terminal 342 connected to the normally open limit switch8LS, and an input terminal 344 connected to the photocell 4PC.

It will thus be apparent that if photocell lPC does not sense thepresence of a sheet of veneer, i.e., if a sheet of veneer is notblocking the ray of light which is received by the photocell, a positivepotential is placed on input terminal 308 of the OR gate circuit 310.Accordingly, a positive potential is placed on the output terminal 311to energize the solenoid 6SOL which causes the engagement of the clutchportion of clutch-brake mechanism 98 to drive feed roller 76a. It willalso be apparent that the solenoid 6SOL can be energized to cause theengagement of the clutch portion of clutchbrake mechanism 98 even if asheet of veneer is fed through the nip rollers 76 to block the beam tothe photocell lPC. This can only happen when the following fourconditions are fulfilled: (1) the outside fence is retracted to sideframe member 129 whereby limit switch 6L8 will be held closed to put apositive potential on input terminal 3180f the AND gate circuit 316, (2)the center fence 82 is retracted against the center stop 203 wherebylimit switch 7LS will be held closed to put a positive potential oninput terminal 320 of'the AND gate circuit 316, (3) the gate 144 is inits upright or closed position whereby limit switch 8LS is held closedto put a positive potential on input terminal 322, and (4there is nosheet of veneer blocking the beam to photocell 2PC adjacent the gate toplace a positive potential on input terminal 324 of the AND gate circuit316.

It will be readily apparent that the solenoid SSOL, as sociated withclutch-brake mechanism 96 and feed roller 740, can be energized in twoways similarly to the energization of solenoid 6SOL except thatphotocells 3PC and 4PC are utilized along with limit switches 6LS, 7LSand 8L8 instead of photocells lPC and 2PC.

As discussed hereinbefore, the outside fence 80 and the center fence 82are mounted for lateral movement in the alignment section 30. Thismovement is controlled by the response from the photocells 2PC and 4PCat the discharge end of the apparatus and by the limit switch 9LS whichsenses the movement of the outer fence 80. These sensing means controlthe actuation of a pair of solenoids 7SOL and 8SOL which operate valves(not shown) that control the flow of air to and, hence, the projectingmovement of the piston rods in pneumatic cylinders 204 and 166respectively. As shown in FIG. 10A, photocells 2PC and 4PC are connectedto the input terminals 350 and 352 respectively of a NOR gate circuit354. The output ofv the NOR gate circuit is connected to the inputterminal 356 of a monostable multivibrator or one shot circuit 358 whoseoutput terminal 360 is connected to the input set terminal 362 of aflip-flop 364 and to the input set terminal 366 of a flip-flop 368.

The photocells 2PC and 4PC are also connected to the input terminals 370and 372 respectively of an AND gate circuit 374. The output of the ANDgate circuit 374 is connected to the input 376 of a one shot circuit 378whose output terminal 380 is connected to the input reset terminal 382of the flip-flop 364. The normally open limit switch 9LS, that is heldclosed when the outside fence 80 is advanced a predetermined distancetoward the side wall 84, is connected to the input reset terminal 384 ofthe flip-flop 368. The output terminal 386 of the flip-flop 368, whoselogic level is O (as indicated) when the flip-flop is set, is connectedto the solenoid 8SOL associated with the outside fence 80.

It can be seen that when sheets of veneer are in the pockets 210 and 212with their forward ends abutting against the gate 144, the rays of lightto the photocells 2PC and 4PC will be blocked that the photocells arenot conducting. Under these circumstances a O potential is on the inputterminals 350 and 352 of the NOR gate circuit 354 so that a positivepotential is placed on the input terminal 356 of the one shot circuit358. This causes a pulse of positive potential to be delivered to theinput set terminal 362 of flip-flop 364 and on the input set terminal366 of the flip-flop 368 to set each of the flip-flops. When theflip-flops 364 and 368 are set, a potential is placed on the outputterminals 388 and 386 of the flip-flops. Accordingly, the solenoids 7SOLand 8SOL are de-energized so that the piston rods of the pneumaticcylinders 204 and 166, respectively, are permitted to be retracted. Whenthe piston rods are allowed to be retracted, the spring 170, which isoperably connected to outside fence 80, pulls the outside fence towardthe side wall 84. As the fence moves toward the side wall, it engagesthe sheet of veneer V2 (FIG. 6) that is in pocket 212 and urges ittoward the side wall. The veneer V2 subsequently engages the centerfence 82 which then is also urged toward side wall 84. The center fence,upon moving toward the side wall 84, engages veneer V1 (FIG. 6) inpocket 210 and urges the veneer V1 into abutment with the side wall. Itcan thus be seen that after this sequence of events the veneer V1 willbe in abutment with the side wall 84 along one side thereof, in abutmentwith the center fence 82 on the other side thereof, and in abutment withthe gate 144 at the forward end thereof. Also, veneer V2 will be alignedalongside sheet V1 being separated therefrom only by the thickness ofthe plate 188 of the center fence. One longitudinal edge of veneer V2will be in abutment with the center fence while the oppositelongitudinal edge thereof is in abutment with the outside fence and theforward end thereof is in abutment with the gate 144. This desiredaligned positioning of the veneer V1 and V2 is shown in phantom lines inFIG. 6.

Just as the outside fence 80 reaches the phantom line position of FIG.6, the switch contacting arm 300, which is carried thereby, will contactand close limit switch 9L8. As can be seen from FIG. 10A, the closing oflimit switch 9L5 places a positive potential on the input reset terminal384 of the flip-flop 368. This resets the flip-flop and reverses itsoutput so that a positive potential is placed on the output terminal 386to energize solenoid SSOL. Energization of 8801. causes the piston rod168 of pneumatic cylinder 166 to extend and drive the outside fence backto its position adjacent side frame member 129. The sheets of veneer V1and V2 will remain in their phantom line positions, however, since theconveyor rollers 78 are angled to urge both sheets of veneer toward theside wall 84.

When operator A at the assembly station 32 is ready for the alignedsheets of middle veneer V1 and V2, he presses one of the switches 34 atthe assembly station to energize a solenoid (not shown) that is operablyconnected to a valve controlling the flow of air to the pneumaticactuator 222 (FIG. 9A) to thereby cause the gate 144 to pivot downwardlyto its open position. When the gate opens the continuously drivenconveyor rollers 78 push the aligned sheets out to the assembly station.When the trailing edge of the sheets of veneer V1 and V2 pass beyond thephotocells 2PC and 4PC, the

respective photocells will begin to conduct. This action minal 376 ofthe one shot circuit 378. This, in turn, causes a pulse of positivepotential to be delivered to the input reset terminal 382 of theflip-flop 364 changing the output of the flip-flop so that a positivepotential is placed on output terminal 388 to energize solenoid 7SOL.Energization of solenoid 7SOL will cause the piston rod 206 of cylinder204 to be extended to drive the center fence 82 back to its retractedposition against the center stop member 203.

As was discussed hereinbefore, the carriage 58, which carries the vacuumheads 62 and 64 in the storage section 28 of the alignment apparatus, ismounted for reciprocal movement whereby it is able to pick up the topsheets of veneer in the stacks M1 and M2 and advance them to the niprollers 74 and 76. The carriage is reciprocated by the double-actingpneumatic cylinder 60 whose functioning is regulated by a solenoid 9SOLwhich operates a two position valve (not shown) controlling the flow ofpressurized air to opposite ends of the cylinder whereby when the solenoid is energized the carriage is caused to move in a downstreamdirection and when it is de-energized the carriage is caused to move ina downstream direction.

The operation of the solenoid 9SOL is controlled by the circuit shown inFIG. 10A. It will there be seen that the photocells lPC and 3PC adjacentthe nip rollers 76 and 74 are connected to the input terminals 396 and398 respectively of an OR gate circuit 400 and to the input terminals402 and 404 respectively of a NOR gate circuit 406. The output of the ORgate circuit 400 is connected to the input terminal 408 of a one shotcircuit 410 whose output is connected to one input terminal 412 of an ORgate circuit 414. A normally open limit switch 10LS (FIG. 1) is mountedon the frame 37 of the storage section 28 adjacent the limit switch 2L8and is disposed so that the carriage 58 will contact and close theswitch when the carriage is retracted to its upstream position. Thelimit switch 10LS is connected to the input set terminal 416 of aflip-flop and to the input reset terminal 420 of a flip-flop 422. Theinput reset terminal 424 of the flip-flop 418 is connected to the outputterminal 426 of the NOR gate circuit 406. The output terminal 428 of theflip-flop 418 is connected to the input terminal 430 of a time delaycircuit 432 which will not conduct a current until a predetermined time(approximately 2 1a seconds in the veneer feeding application disclosed)after a positive potential has been placed on the input terminal 430.The output terminal 434 of the time delay circuit 432 is connected tothe other input terminal 436 of the OR gate circuit 414 whose outputterminal 438 is connected to the input set terminal 440 of the flop 422.

The output terminal 442 of flip-flop 422, which has a logic output 1 (asindicated) when the flip-flop is set is connected to one input terminal444 of an AND gate circuit 446 whose output terminal 448 is connected tothe solenoid 9SOL for effecting reciprocation of the carriage S8. Theother input terminal 450 of the AND gate circuit 446 is connected to theoutput terminal 452 of a NAND gate circuit 454 whose two input terminals456 and 458 are connected to the normally closed limit switches 2LS and4L8 respectively which are held open by the stacks M1 and M2 of veneerand which will only be allowed to close after the last sheet of veneerin the associated stack M1 or M2 has been removed.

It will be apparent from the aforedescribed circuitry that when thereare stacks MI and M2 of veneer in the storage section 28 so that thelimit switches 2LS and 4LS are held open a positive potential will beplaced on the output terminal 452 of the NAND gate circuit 454 and onthe input terminal 450 of the AND gate circuit 446. If at least one ofthe sets of nip rollers 74 and 76 has no veneer protruding therethroughso that at least one of the photocells lPC or 3PC is conducting, the oneshot circuit 410 will deliver a pulse to the input terminal 412 of theOR gate circuit 414. This will cause a positive potential to be placedon the input set terminal 440 of the flip-flop 422 to set the flip-flopso that a positive potential will be placed on the output terminal 422and the input terminal 444 of the AND gate circuit 446. Since the limitswitches 2LS and 4LS are held open by the stacks of veneer M1 and M2during the feeding of the sheets to the alignment apparatus, a positivepotential will be placed on the output terminal 452 of the NAND gatecircuit 454 thereby placing a positive potential on the other inputterminal 450 of the AND gate circuit 446. With a positive potential onboth input terminals of the AND gate circuit 446 a positive potentialwill be placed on the output terminal 448 to energize the solenoid 9SOL.As'stated hereinbefore, when the solenoid 9SOL is energized the pistonrod of the pneumatic cylinder 60 is caused to retract to draw thecarriage in an upstream direction. When the carriage reaches its extremeretracted position, it will close the normally open limit switch 10LSwhich sets the flipflop 418 and resets the flip-flop 422. When theflip-flop 422 is reset, the positive potential on the output terminal422 is removed consequently removing the positive potential on theoutput terminal 448 of the AND gate circuit 446 to deenergize thesolenoid 9SOL. This causes the piston rod on the pneumatic cylinder 60to extend forcing the carriage 58 to move in the downstream directioncarrying with it, via the vacuum heads 62 and 64, two sheets of veneer.The sheets of veneer picked up by the vacuum heads are fed into the niprollers 74 and 76 which continue to advance the veneer until the lightrays to both photocells lPC and 3PC have been broken. The closing oflimit switch 10LS, in addition to initiating the return movement of thecarriage, also sets the flip-flop 418 so that the time delay circuit 432is energized. If the light beams to both of the photocells IPC and 3PCare not broken within the predescribed time (about 2 k seconds) to resetthe flip-flop 418 through the NOR gate circuit 406 and therebyde-energize the time delay, a positive potential will be placed on theinput terminal 436 of the OR gate circuit 414 by the time delaycircuitry. A positive potential on the input terminal 436 will again setthe flip-flop 422 and thereby energize the solenoid 9SOL through the ANDgate circuit 446 to cause the carriage to move upstream again. If,however, a sheet of veneer is fed from each stack M1 and M2 into the niprollers 74 and 76 within the required time (which will occur if twosheets are picked up by the vacuum head) then the flip-flop 418 will bereset before the solenoid 9SOL can be energized and the carnage will beleft in its downstream position to allow the sheets to be fed into thealignment apparatus. As soon as the trailing ends of the sheets havepassed beyond the photocells lPC and 3PC so that the photocells areagain conducting, the solenoid 9SOL will again be energized through ORgate circuit 400, one shot circuit 410, OR gate circuit 414, flip-flop422, and the AND gate circuit 446 to cause the carriage to again moveupstream to pick up another pair of sheets. It will be apparent that ifby chance one of the vacuum heads 62 or 64 does not pick up a sheet ofveneer, the carriage will be caused to retract and pick up the missingsheet and will continue to thus recycle until a sheet is in both of thenip rollers blocking both photocells IPO and 3PC.

The operation of the alignment apparatus 20 will further be understoodby reference to FIGS. 11A through 11D wherein diagrammatic plan views ofthe apparatus in its difi'erent stages of operation are shown. In FIG.11A a portion of the stacks M1 and M2 of veneer are shown in the storagesection 28 with the uppermost sheet V1 and V2 of the respective stacksadvanced through the nip rollers 74 and 76 whereby the downstream end ofthe sheets are blocking the photocells 3PC and lPC respectively. Thevacuum heads 62 and 64 are stationary at this time. It will be notedthat the outside fence 80 and the center fence 82 are in their retractedpositions and that the gate 144 is in its closed position with thephotocells 4PC and 2PC unblocked and therefore conducting. Under thisset of conditions, the feed rollers 74a and 76a are caused to be drivenso that the sheets V1 and V2 are advanced into the pockets 210 and 212of the alignment section 30.

Once the sheets V1 and V2 are into the alignment section 30 they will besupported by the conveyor rollers 78 which advance them into abuttingcontact with the closed gate 144 (FIG. 11B). As soon as the trailingends of the sheets passes beyond the photocells 3PC and IPC, thecarriage carrying the vacuum heads 62 and 64 is retracted to pick up thenext pair of sheets V3 and V4 in each stack (FIG. 11B).

When the sheets V1 and V2 are moved over the photocells 4PC and 2PC sothat these photocells no longer conduct, the outside fence 80 is causedto move laterally toward the center fence 82. As the sheet V2 becomespinched between the two fences, the center fence is forced toward theside wall 84 and pushes the sheet V1 in the same direction. Ultimately,sheet V1 is aligned with and abutting against the side wall 84 and sheetV2 is aligned with and abutting against the center fence 82 (FIG. 11C).When the two sheets V1 and V2 become aligned, the outside fence will beretracted, as indicated by the directional arrows in FIG. 11C, and willremain retracted until the next two sheets V3 and V4 are advanced intothe alignment section. The center fence 80, however, does not retractuntil after the sheets V1 and V2 have been advanced out of theapparatus, and the sheets cannot move out of the apparatus until theoperator opens the gate 144 to allow the conveyor rollers 78 to movethem out.

In FIG. 11D, the sheets V1 and V2 have been moved out of the apparatus,and the next two sheets V3 and V4 are being advanced into the alignmentsection 30 where an identical sequence of operations will take place toalign them and subsequently move them out of the apparatus.

From the foregoing description it will be appreciated that the apparatusof the present invention provides a means whereby sheets of relativelyfragile material, such as plywood veneer, can be aligned on a conveyorand placed in abutting side-by-side relationship. The apparatus willoperate efficiently without jamming and without causing overlapping ofthe sheets or damage to the sheets.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

What is claimed is:

1. An apparatus for aligning sheets of material in side-by-siderelationship comprising in combination a frame having an input end andan output end, conveyor means mounted on said frame for advancing saidsheets of material from the input end to the output end of the frame, agate at said output end which is alternately movable between open andclosed positions, means for moving said gate between said open andclosed positions, a stationary side wall extending substantially fromthe input to the output end of said frame along one side thereof, afirst fence means extending. substantially parallel to said side wallalong the other side of said frame and being mounted for movement towardand away from said side wall, a second fence means extendingsubstantially parallel to said first fence means between said firstfence ineans and said side wall and also being mounted for movementtoward and away from said side wall, said first and second fence meanshaving retaining means for selectively holding the fence means in theirpositions furthest removed from said side wall, means operativelyassociated with said first fence means for moving said first meanstoward said side wall, and control means for controlling said movementof said first and second fence means.

2. The apparatus of claim 1 further including feeding means near saidinput end for selectively feeding sheets of material between said sidewall and said second fence means and between said second fence means andsaid first fence means.

3. .T he apparatus of claim 2 wherein said feeding means includesrotatably mounted nip rollers having parallel axes of rotation, saidrollers being spaced such that the sheet material cannot passtherebetween unless the nip rollers are rotated.

4. The apparatus of claim 3 including drive means for selectivelyrotating one of said nip rollers. flip-flop 442.

5. The apparatus of claim 1 wherein said conveyor means includes aplurality of rotatably mounted conveyor rollers having their rotationalaxes extending transversely of said side wall and said fence means, saidconveyor rollers having one end rotatably mounted adjacent said sidewall and the other end rotatably mounted adjacent said first fence meanswhen said first fence means is in its farthest removed position fromsaid side wall.

6. The apparatus of claim 5 further including means for rotating saidconveyor rollers in a manner such that the sheet material supported bysaid conveyor rollers will be moved from the input to the output end ofsaid frame.

7. The apparatus of claim 6 wherein the end of each of said conveyorrollers mounted adjacent said first fence means is closer to the outputend of said frame than the corresponding end of each of said conveyorrollers mounted adacent said side wall whereby sheet material supporteby said conveyor rollers will be urged toward said side wall as it ismoved toward the output end of said frame.

8. The apparatus of claim 1 wherein said retaining means for said firstand second fence means comprises first and second power cylindersrespectively each having extensible piston rods for operably engagingsaid first and second fence means.

9. The apparatus of claim 8 wherein said means for moving said firstfence means toward said side wall comprises resilient means biasing saidfirst fence means toward said side wall.

10. The apparatus of claim 1 further including storage means for storingstacks of the sheet material and means for delivering pairs of sheetsfrom said stacks to said frame.

11. The apparatus of claim 10 further including control means forcontrolling the operation of said delivery means so that said sheetmaterial is only delivered to said frame when said frame is empty.

12. The apparatus of claim 11 wherein said control means includes sheetsensing means adjacent said sheet delivery means and adjacent said gatefor sensing the presence or absence of sheets of material at therespective locations.

13. The apparatus of claim 12 wherein said sheet sensing means comprisephoto-electric cells.

14. The apparatus of claim 11 wherein said control means includesdetection means for detecting the presence of said first and secondfence means in their positions furthest removed from said side wall.

1. An apparatus for aligning sheets of material in side-by-siderelationship comprising in combination a frame having an input end andan output end, conveyor means mounted on said frame for advancing saidsheets of material from the input end to the output end of the frame, agate at said output end which is alternately movable between open andclosed positions, means for moving said gate between said open andclosed positions, a stationary side wall extending substantially fromthe input to the output end of said framE along one side thereof, afirst fence means extending substantially parallel to said side wallalong the other side of said frame and being mounted for movement towardand away from said side wall, a second fence means extendingsubstantially parallel to said first fence means between said firstfence means and said side wall and also being mounted for movementtoward and away from said side wall, said first and second fence meanshaving retaining means for selectively holding the fence means in theirpositions furthest removed from said side wall, means operativelyassociated with said first fence means for moving said first meanstoward said side wall, and control means for controlling said movementof said first and second fence means.
 1. An apparatus for aligningsheets of material in side-by-side relationship comprising incombination a frame having an input end and an output end, conveyormeans mounted on said frame for advancing said sheets of material fromthe input end to the output end of the frame, a gate at said output endwhich is alternately movable between open and closed positions, meansfor moving said gate between said open and closed positions, astationary side wall extending substantially from the input to theoutput end of said framE along one side thereof, a first fence meansextending substantially parallel to said side wall along the other sideof said frame and being mounted for movement toward and away from saidside wall, a second fence means extending substantially parallel to saidfirst fence means between said first fence means and said side wall andalso being mounted for movement toward and away from said side wall,said first and second fence means having retaining means for selectivelyholding the fence means in their positions furthest removed from saidside wall, means operatively associated with said first fence means formoving said first means toward said side wall, and control means forcontrolling said movement of said first and second fence means.
 2. Theapparatus of claim 1 further including feeding means near said input endfor selectively feeding sheets of material between said side wall andsaid second fence means and between said second fence means and saidfirst fence means.
 3. The apparatus of claim 2 wherein said feedingmeans includes rotatably mounted nip rollers having parallel axes ofrotation, said rollers being spaced such that the sheet material cannotpass therebetween unless the nip rollers are rotated.
 4. The apparatusof claim 3 including drive means for selectively rotating one of saidnip rollers. flip-flop
 442. 5. The apparatus of claim 1 wherein saidconveyor means includes a plurality of rotatably mounted conveyorrollers having their rotational axes extending transversely of said sidewall and said fence means, said conveyor rollers having one endrotatably mounted adjacent said side wall and the other end rotatablymounted adjacent said first fence means when said first fence means isin its farthest removed position from said side wall.
 6. The apparatusof claim 5 further including means for rotating said conveyor rollers ina manner such that the sheet material supported by said conveyor rollerswill be moved from the input to the output end of said frame.
 7. Theapparatus of claim 6 wherein the end of each of said conveyor rollersmounted adjacent said first fence means is closer to the output end ofsaid frame than the corresponding end of each of said conveyor rollersmounted adjacent said side wall whereby sheet material supported by saidconveyor rollers will be urged toward said side wall as it is movedtoward the output end of said frame.
 8. The apparatus of claim 1 whereinsaid retaining means for said first and second fence means comprisesfirst and second power cylinders respectively each having extensiblepiston rods for operably engaging said first and second fence means. 9.The apparatus of claim 8 wherein said means for moving said first fencemeans toward said side wall comprises resilient means biasing said firstfence means toward said side wall.
 10. The apparatus of claim 1 furtherincluding storage means for storing stacks of the sheet material andmeans for delivering pairs of sheets from said stacks to said frame. 11.The apparatus of claim 10 further including control means forcontrolling the operation of said delivery means so that said sheetmaterial is only delivered to said frame when said frame is empty. 12.The apparatus of claim 11 wherein said control means includes sheetsensing means adjacent said sheet delivery means and adjacent said gatefor sensing the presence or absence of sheets of material at therespective locations.
 13. The apparatus of claim 12 wherein said sheetsensing means comprise photo-electric cells.